Epizooplankton vertical distributions shaped by physical processes

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Marine Biology and Fisheries

First Committee Member

Peter Ortner - Committee Chair

Second Committee Member

Larry Brand - Committee Member


Fine-scale (1-10 m) patterns of vertical epizooplankton distribution were compared with synoptic physical parameters to assess how these distributions are shaped by physical processes. Contrasting points of reference and sampling schemes reveal how processes with different temporal and spatial scales interact and affect our observations. The primary instrumentation was an in situ plankton camera system measuring conductivity, temperature, fluorescence and zooplankton abundance with 1 meter depth resolution and an RDI Acoustic Doppler Current Profiler.Fine-scale vertical zooplankton and physical distributions across the Alaska Coastal Current (ACC) revealed the presence of a front separating distinctive coastal and oceanic zooplankton communities. For many zooplankton taxa, abundances varied across the front by more than an order of magnitude. Since a coastal flow is reported along most of the southern Alaska shelf, frontal processes may concentrate a significant portion of the zooplankton prey and provide enhanced feeding opportunities for commercially important fish species.During a Lagrangian drift through a Gulf Stream meander, the vertical distribution and abundance of macrozooplankton was modified by the physical dynamics of the meander. Within the surface convergence of the meander's trough macrozooplankton were enhanced in abundance.Differential diffusion of the enhanced zooplankton after the meander was passed was attributed to swimming abilities of the taxa.A multivariate analysis of the fine-scale vertical codistribution of zooplankton and turbulence found an association between high turbulence and immobile plankton taxa (foraminiferans, radiolarians and larvaceans). However, for at least the larvaceans, the statistical association on the fine-scale may actually be due to mesoscale processes of the meander dynamics.


Biology, Ecology; Biology, Oceanography

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Link to Full Text